User's Manual

Introduction to Network Security
2 WatchGuard Firebox X Edge
Computer security must always be kept up-to-date. Intruders are
always discovering new vulnerabilities to exploit in computer soft-
ware.
About Networks
A network is a connected group of computers and other devices. It
can consist of anything from two computers connected by a serial
cable to thousands of computers connected by high-speed data
communication links located throughout the world.
A
Local Area Network (LAN) is a group of computers linked electron-
ically to form a common work environment. This facilitates the shar-
ing of applications and data, and is especially important when a
group of people need to work together on one project.
A
Wide Area Network (WAN) involves computers separated by signif-
icant distances, such as those located in different buildings.
Clients and servers
The terms client and server are used to describe individual comput-
ers that are part of a network. A server is a computer that makes its
resources available to the network and responds to the commands
of a client. Examples of a server’s shared resources are files (a file
server), printers (a print server), and processing power (an applica-
tion server). A client is a computer that uses the resources made
available by the server.
Connecting to the Internet
You have a number of options for connecting to the Internet. High-
speed Internet connections, such as cable modem or Digital Sub-
scriber Line (DSL), are referred to as broadband connections.
Band-
width
describes the relative speed of an Internet connection, such as
1 Megabit per second (Mbps).
You can use a cable modem to connect to the Internet via the cable
TV network. The cable modem usually has an Ethernet LAN connec-
tion to the computer, and it is capable of speeds in excess of 5
Mbps.
Typical speeds tend to be lower than the maximum, however,
because cable providers turn entire neighborhoods into LANs that